Electrical protective device.



I. ROSENBLUM.

ELECTRICAL PROIECTIVE DEVICE. APPLIcAloN FILED 00119194.

1,198,962. Patented sept. 19,1916.

Witnesses Iventor;

al Israel Rosenblum,

Hisqtt-,ornmg- ,Y

Y terials,

yat Lynn, in the V ample, as carbon.

any desired voltage rang ISRAEL ROSENBLUM, OF LYNN, MASSACHUSETTS,

ASSZGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

ELEcTR'IcAL PROTECTIVE nevrosi.

To all wlwm z'zf may concern.'

e it known that a subject of the King of Roumania, residing county of Essex, State of Massachusetts, have invented certain new characteristics.

ile my invention ence to the utilization 'cut-out devices, struction is likewise applicable to similar n as silicon. n accordance with one feature of my invention I l a film of boron is united to a material of relatively high conductivity, such, for ex- An intimate union is produced by chemically depositing at high temperature a iilrn of oron on a conductor of carbon, boro-carbon, tungsten, or the like, and by depositing in turn upon the boron` a layer of one of these thereby producing a unitary struclias particular .referof boron 1n electrical turc.

Another feature of iny invention is a cut- In the accompanying drawings Figure l shows in section a simple forni oi boron cutout greatly tion in which a'sectional view of a boron-cut-out mounted and provided with terminals Specification of Letters Patent. Application filed Dctober 19,1914.

I, ISRAEL ROSENBLUM,

the principle of its conmagnified; Fig. 2 is a modiica- V Patented Sept. 19, 193m. Serial No. 867,328.

suitable for convenient insertion into clipsSOy or similar contact-making devices. ,l oron because or its high electrical resistl ance and very high negative temperature'copeculiarly adapted"v cut-out material, bitf the very great hardness, crystalline and brittle character of oren and, its oxidizaa thin layerin cut-outs designed to be ed at a moderate voltage, and that contacts must be provided which will not unneces sarily raise the resistance will not vary in resistance when heated by a passage of current.

ecause of the physical properties of boron diliculties are experienced with the mainte-l` nance of the electrical contacts. Mechanical contacts and soldered contacts have proved to be not reliable.

y cutout preferably takes the form of a rod-like bo y, as shown greatly inagnified in Fig. l. The core l consists of conductive material, preferably of boro-carbon. The borocarbon may be prepared by Squirting linely divided boron with pitch and can` oni'zing the product, the amount of pitch introduced being varied in'accordance lWithMS the break-down voltage desired.

increase the conductivity of the core. Upon f a layer. of boron 2 by" heating the core in ainixtureof boric chlorid and hydrogen, as described in UTS. Patent #1,019,393 to E. ilfeintraub. Mechanif" cal shaping of the brittle boron is thuS- avoided and an vintimate adherence is Seri/, free'from soldering ma- '9,01

he deposition` ternperatureand grop'ortions I CIK ' layer of i i voltage or boron is best adjusted by introducinp,` a very small but definite quantity et' carbon. rThe above lVeintraub Patent #1,019,393 discloses a method of adding carbon to boron by depositing; the boron and carbon simultaneously from a mixture 0i boric chlorid and hydrocarbon, but because the amounts ot carbon required in the boron layer of a cut-out are extremely minute, this method ordinarily is not refined enough.

l have found that by using a base filament of boro-carbon and depositing; boron on this base enough carbon may be transferred from the base te the deposited boron to give the necessary adjustment of breakdown voltage. By increasing the amount of carbon in the base greater amounts or carbon may be transferred to the boron layer.

The conductor thiis prepared is then incandesced in a hydrocarbon atmosphere, such as a vapor et benzol, gasolene, carbon tetrachlorid, or the like, until a layer 3 ot carbon of suitable thickness has been deposited. Here a gain an intimate molecular adherence ot the carbon to the boron is secured and an electrical contact is provided which is unaffected by thermal changes.

Ii' but a single layer of boron is to be included in the electrical circuit the end oi' the core l may be exposed by grinding ol' part ot the deposited layers, the carbon beine; rcmoved from aliexccpt the end, as shown in Fig. i. lt, on Vthe other hand the breakdown of two layers of boron is desired, the layer of boron and the hns ot' carbon 3, may he allowed to remain at each of the end portions as shown in Fig. 2. As sho'wnvin Fig. 3, a unit thus constructed may be provided with terminal sleeves 5, G, preferably consisting,` o't' lgraphite, and simply making a mechanically tight fit with the deposited carbon. A unit thus made is slipped into a protective sheath 7 ot' glass or other non-conducting material i metallic end caps f), which may have conductive stems 10, 11 centering and holding the graphite sleeves. When a unit thus constructed is connected in shunt with device, such as a series connected arc lamp or iu.- candcscent lamp, and the yvoltage across its terminals rises above the value at which the boron layer has been proportioned to break down in resistance, an electrical lcircuit is established from the layer of carbon 8 through the layer of boron to the core l, to which contact may be made in the simple 'torment' cut-out shown 'in Fig, 1, or from the core through another layer ofboron to the second layerl ot carbon, as shown in llfigs. 2 and 3. o

Cut-ou s as above described may be iliade 'to break down at any commercial voltage, :tor example, from 569 'volts down and. will and providedwithv incense be substantially invariable in their break down characteristic between suc ssire pc-- .riods ot' operation. rllhe voltage ransi'c ir'uhin which the cut-out may be constructed to break down can be adjusted not only by varying the thickness ot the boron lil-In, the temperature, the concentration ot boron vapors and other Jfactors during the treatment and 'the percentage ot carbon in the boro-carbon base, as above indicated, but also by varying; the surtace ot the contact between the carbon or other conductive terminal and the boron, and the degree ot heat dissipation effected by the terminals; .as pointed out in 1Thomson Patent No. 1,063,305, an increase in the size oit the heat ra dieting members in contact with the boron increases the voltage and lengtheus the time necessary. for causing the breakdown ot the boron film. It is, therefore, dillicult to give any specific example, but it will be .obvious by varying any or all of these means ot aobe constructed tor justment cnt-outs may any desired service.

lli/That I claim as new and desire to secure by Letters Patent of the United States, is 1* i. An electrical cut-out comprising a filmlike body oit extended surface consisting largely of boron and bodies o'l' highly conductive material molccnlarly adhering to opposite surfaces or' said boron body to form a unitary structure.

2. An electrical cut-out comprising,- a {ihnlikc body ot' extended surit'ace consisting largely ot boron and bodies ot' carbon molec'ularly united therewith.

3. n electrical cut-out comprising a fihn ot boron associated with carbon, and bodies of highly conductive material inolecularly adhering, thereto.

et. An. electrical cut-out comprising a. core ot conductive material, a layer consisting largely ot' boron inolccularly united thereto, and a layer of' carbon molecularly united with said boron layer.

An electrical cut-out comprising' a rod et boro-carbon, a relatively thin layer ot boron deposited thereon and adheringintimately thereto, a layer oi carbon deposite( on said boron and adhering thereto, and conductors contacting: respectively with said rod and carbon layer.

(i. An electrical cut-out comprising a rodlike body consistingof: boron and. carbon, a layer of boron united with said body, layers of carbon covering;` the end portions only oi': said boron layer and intimately uuitcd therewith, sleeves ot graphite uuazhanicall y inclosing; said carbon layers and making electrical contact therewith.

7. fin electrical cutout consisting of :L rod-like body ot inno-carbon aud a. layer of boron uiolecularly united therewith, layers 5 carrying'terniinals`\for said gra 1,198,962" 3 of. lcarbon intimately united with 4the end' layer of carbon molecillarly united with said `portionsv of said' boron layer, vgraphite boronlayers sleeves m chemically fitted to -said carbon In -witness whereof, Il have' hereunto set ln'yers lat ernchendof said body, and culrentmy hand this fifteenth day of October, 1914.

phite sleeves. AEL ROSENBLUM.` An electrical .cu -out comprising a core Witnesses:

` o ro-carbon, a-lmconsisting largelyof v lJOHN ArMCMA-NUS, Jn, oron` mlecularly `united thereto `and` a oHN T. BEECIILYN. 

